docs: def com_google_fonts_check_mandatory_glyphs(ttFont):
    """Font contains .notdef as first glyph?
  
    The OpenType specification v1.8.2 recommends that the first glyph is the
    .notdef glyph without a codepoint assigned and with a drawing.
  
    https://docs.microsoft.com/en-us/typography/opentype/spec/recom#glyph-0-the-notdef-glyph
  
    Pre-v1.8, it was recommended that a font should also contain a .null, CR and
    space glyph. This might have been relevant for applications on MacOS 9.
    """
    from fontbakery.utils import glyph_has_ink
  
    if (
      ttFont.getGlyphOrder()[0] == ".notdef"
      and ".notdef" not in ttFont.getBestCmap().values()
      and glyph_has_ink(ttFont, ".notdef")
    ):
      yield PASS, (
        "Font contains the .notdef glyph as the first glyph, it does "
        "not have a Unicode value assigned and contains a drawing."
      )
    else:
      yield WARN, (
        "Font should contain the .notdef glyph as the first glyph, "
        "it should not have a Unicode value assigned and should "
        "contain a drawing."
      )